Asterisk SIP ERROR 408

I have a server in the cloud of ip 300.432.210.23, and I mounted an asterisk server, but I am not able to register channels, every time I try to receive the message SIP error 408,
Can it be port release problem or some lack of configuration?
ps: it is worth remembering that the server is not local.

SP 408 is “Request Timed Out” and is usually faked by the a client that doesn’t receive a response. Lots of things can cause it.

but and now? how to get around the problem?

You trace the request through your network,and, if Asterisk receives it, trace the response back, until you find where it is being lost or corrupted.

The most likely causes are NAT and firewall misconfiguration.

Note the server running the Asterisk daemon, will normally have its own firewall.